Electrical metal fusing apparatus and method



Nov. 3, 1942. K, op 'ms 2,300,670

ELECTRICAL METAL FU SING APPARATUS AND METHOD Filed May 21, 1940 wnr W9INVENTOR ROBERT K. HOPKINS l2 BY A 15g V A ORZEY Patented Nov. 3, 1942 IELECTRICAL METAL rusmc ArrAaA'rUs I AND METHOD Robert K. Hopkins, NewYork, N. Y., assignor to The M. W. Kellogg'Co New York, N. Y., acorporation of Delaware Application May 21, 1940, Serial N6. 336,340

' 10 Claims.

This invention relates to the electrical fusion of metalsandparticularly to the type of operation in which metal is deposited byfusing its constituents at a gap through which electric current isdischarged.

' In the electrical fusion of metals, wherein metal is fused by thedischarge of electric current through a gap, it is the usual practice toemploy an electrode, either of metal made up of constitucuts of thedesired metal or of non-consumable material, as one terminus of the gap.The operation is most generally controlled by adjusting the end of theelectrode relative to theother terminus of the gap as required tomaintain an electrical discharge of substantially. constantcharacteristics. This adjustment is efiected by arrangements connectedto the electrical discharge circuit which act upon the electrode feedthe electrode to the gap at a constant rate and adjusting the electricalenergy imput to the gap as required to fuse the electrode at a constantrate.

It is a primary object of the invention to provide a novel method, andnovel apparatus for carrying it out in practice, for the electricalfusion 'of metals wherein metal is fused by the discharge of electriccurrent through a gap between the end on an electrode and a conductivebody, the electrode being supplied to the gap at a constant rate and thecurrent discharged at the gap being varied inversely as the resistanceof the gap varies to fuse the electrode at a constant rate.

It is also a primary object of the invention to provide a novel method,and novel apparatus for carrying it out in practice, for producing metalmotor, or other equivalent means. By reason of the mass of the movingelements, andtheir necessary mechanical connections, this manner ofcontrol does not result in an instantaneous adjustment so that thecharacteristics of the electrical dischargeand'the fusion rate of theelectrode are not maintained constant at predetermined values butactually constantly vary, or hunt, about the predetermined values. Thevariations are such, however, that they average and for any practicalrun the quantity of metal that will fuse can quite accurately bepredicted. I

This manner of control, while satisfactory for operations in which themetal fused is derived from the electrode and the base metal, imposeslimitations in operations wherein constituents of a final metal of adesired analysis are supplied from sources other than the electrode, orthe base metal, or the electrode. andthe base metal, at

rates uneflfected by, the variations at the gap. In

' the latter operations, as-for instance, those contemplated in my priorPatent No. 2,191,471, it is necessary in order to secure uniformanalysis with this typeof control, to operate under such condltlons thatthere is always present a sufllciently large body of molten metal toaverage up the variations in the supply of electrode metal.

The use ofthis expedient for avoiding nonuniform analysis does notordinarily affect the efllciency of the process but, in special cases,imposes a limit on the speed at which it can be. carried out. Thus, whendepositing a thin coating of alloy on a base metal the speed of traverseof the electrode over the base metal and the rate of production of thealloy must be kept down to the values at which asumciently large body ofmolten metal is present to average the varying rate of fusion.

I have found that superior results can be ob-' tained in the generaltype of operation and the mentioned limitation to the specific operationremoved, for all practical purposes. by supplying.

of desired analysis by the fusion-of its constituents at a gap, betweenan electrode and a conductive body, through which electric energy isdischarged, wherein one or more of the constituents of the desired metalare supplied to the gap in' the form of ametal electrode and another orothers of the constituents are supplied to be fused with the metal ofthe electrode, from a source separate from said electrode, the electrodebeing supplied to the gap at a constant rate, the other, or others, ofthe constituents being also supplied at a constant rate and theelectriccurrent imput to the gap being varied inversely as theresistance of the gap varies so as to fuse the electrode at a constantrate whereby the fused metal is made up throughout of a predeterminedproportion of the constituents supplied by the electrode and theconstituents supplied from the separate source. I

It is a further primary object of the invention to provide a novelmethod, and novel apparatus for carrying it out in practice, forproducing metal of desired analysis by the fusion of its constituents ata gap, through which electric current is discharged, between anelectrode and aconductive body, wherein one or more of the constituentsof the desired metal are supplied to-the gap in the form of a hollowmetal electrode and another mothers of the constituents are sup-. pliedin particle form to the gap through the hollow electrode to be fusedwith the metal of the electrode, the hollow electrode being supplied tothe gapat a constant rate, the material in particle form also beingsupplied at a constant rate and the electric current imput to the gapbeing varied inversely as the resistance of the gap varies to fuse themetal of the electrode at a constant rate whereby a predeterminedpropor-' 7 tion between the constituents supplied by the hollowelectrode and the material in particle form is constantly attained inthe fused metal.

The further objects and advantages of the invention will be apparentfrom a consideration of All the following description, taken with theaccompanying drawing, in the single figure of which, is shown a frontview of a preferred form of the apparatus of the invention.

The method and the apparatus of the invention are applicable generallyto electrical metal fusing operations wherein metal is fused at a gapthrough which electric current is discharged between an electrode and aconductive body. Thus, they are applicable to seam welding, either ofthe open or submerged arc type, and when the defposited metal is ofsubstantially the same analysis as that of the metal to be joined or isof different analysis from that of the metal to be Joined. They are alsoapplicable to coating or veneering operations, 1. e., operations inwhich composite metal bodies are formed by depositing molten metal ofone analysis on a surface of a base metal of a different analysis tounite the metals into an integral structure. Furthermore, they are alsoapplicable to operations in which alloy bodies of a single analysis areproduced.

I choose to disclose my invention in detail in connection with themanufacture of an alloy body of a single analysis throughout. Also,while the invention is not limited to the use of a hollow electrode;solid electrodes, composite electrodes, etc., may also be used, I willdisclose it in detail in connection with a hollow electrode.

The electrical metal fusing machine I. with the exceptions of certainelements not necessary to the present disclosure approximates thatdisclosed in my prior Patent No. 2,191,476 and, hence, the commonelements will not be gone into in detail here.

Machine I is supported on a suitable structure H for movement in alldirections over mold l2. Mold i2 is shown as a water cooled metal mold,preferably of copper; however, any preferred mold suited to theparticular operation may be employed, thus, even a refractory mold maybe employed. When the invention is used in seam welding or in thecoating of metal bodies, the bodies to be united or the base metal to becoated is substituted for mold -I 2.

Within housing It is the tube forming mechanism that converts flat stripi into the hollow pipe like electrode 15., Strip I4 is made of aconstituent, or constituents, of the ultimately desired metal and isconveniently carried on reel Ii. The

formed hollow electrode passes from the tube forming mechanism through acontact nozzle II from whence it proceeds towards mold l2. A vibratordevice It may be provided adjacent nozzle II to prevent clogging of theend of hollow electrode II.

The tubeforming mechanism is driven by shaft I! that is connected bygears, in gear-box 20. to the shaft 2| of motor 22. Motor 22, since itoperates the tube forming mechanism, is the feed motor for hollowelectrode l5 and in any particular operation is operated at a constantspeed. To give the apparatus a degree of flexibility, so that it may beused generally in the type of operation contemplated, motor 22 may be ofsuch kind that it can be operated at any speed within a predeterminedrange of speeds, or it may be a single speed motor and a speed changingdevice, not shown, provided between it and shaft ll of the tube formingmechanism.

Contact device I! is connected through cable 22 to one side of theoutput of generator 24, the other side of the output is grounded throughcable 25 to metal mold l2. Generator 24 may be such as to generate A. C.or D. 0. current, as

preferred and will normally be driven as by motor 25.

The field windings of generator 2 are tapped by wires 21 and 28 so as toplace variable resistance device 29 in the field circuit. Thearrangement is preferably such that device 29 is in series with thefield windings. Device 29 may be of any preferred form but must functionto cut resistance into the field circuit as the voltage across theoutput cables increases and cut resistance out of the field circuit asthe voltage across the output cables decreases. A number of commercialdevices suited for this purpose are available. I

have shown schematically a device 29 that will function as required.

Device 29 includes a resistance 30 that is connected to wire 28. Thecontact end of pivoted contact bar 3| is adapted to make contact withresistance 30 as it is moved over the surface of resistance 30 to changethe ohmic value of the resistance .in the field circuit to thus alterthe field excitation and, consequently, the current output of generator2i. Contact bar 3| is connected at its pivot to wire 21. The other endof bar 2| is connected by suitable linkage to the metal core 32 ofsolenoid 23. Wires 3! and 35 shunt solenoid 23 across cables 22 and 25.A spring 36 constantly tends to pull contact bar 3| to the zeroresistance contact point.

On a platform 31 above housing ii are mounted metering devices 38. Thesedevices are preferably of the type shown and described in my priorPatent No. 2,174,175, although metering devices of any comparable typemay be employed. Six devices 28 have been shown but a greater or lessernumber may be used as required. Each device 28 is provided with a hopper29 in which is placed the particular granular material to be metered bythe particular device. The metered materials pass into a common hopperID from whence they pass through tube ll into the formed hollowelectrode ii. The granular materials are alloys or pure metals made upof constituents of the final desired metal.

Metering devices 2! are driven by shaft 42 that is connected to theoutput of the combined clutch and speed changer box 42. The input of box42 is connected to the shaft of motor 44. Motor 14 is of the constantspeed type so that the materials metered are supplied into hollowelectrode ii at a constant rate throughout the operation of theapparatus.

In the deposition of ferrous alloys such as the chrome-irons or thechrome-steels; chrome! nickel steels. etc., strip ll will usually be alow carbon iron or steel, Armco iron, for example, and the granularmaterlals supplied into hollow electrode i5 ferro-alloys such asferro-chrome, ferromanganese, etc., or pure metal such as nickel, etc.

In the production of an alloy ingot of a desired analysis, knowing theanalysis of the chosen material of strip H as well as the analysis ofthe chosen granular materials to be supplied into hollow electrode II,and the preferred fusing capacity of the apparatus, it is a simplematter to determine the metering rates of the granular materials and thefeed rate of hollow electrode ll. Experience will indicate in each casethe preferred resistance across the current discharge the bottom-of moldi2. To facilitate starting, the

hollow electrode is fed almost to-the surface of the metal plug and awad of steel wool, or similar are starter interposed between theelectrode and the plug. The electrode end, as well as the bottom of themold, are then covered with a deep blanket of protective flux 45. Themotor is the energized and the operation commenced, after themotor-generator set has come up to speed, by closing the generatoroutput circuit and the circuits of motors 22 and 44.

The initial current surge destroys the arc starterto establish adischarge gap, beneath flux blanket 45, between the electrode and themetal plug. As the initial fiow is at short circuit, the initialenergization of solenoid 33 will be insufficient to pull contact arm 3|off the no re- 'sistance stop, however, as the gap forms the voltagerises and increases the energization of the solenoid so that contact armwill be moved over the resistance to cut it into the field circuit andthus reduce the current output of the generator. until the gap isbrought'to the predetermined ohmic value; when the rate of fusion ofelectrode It will equal its rate of speed.

During the operation, for various causes, the.

resistance of the gap will change. When such changes occur the voltagein the energizing circult of solenoid 33 will change and bar 3| will bemoved to change the resistance in the generator This movement of bar 3|will continue field circuit to vary the. current output inversely as theresistance of the gap varies. Thus, if the resistance of the gapincreases, bar 3| will move to cut more resistance into the generatorfield circuit to diminish the current output until the resistance of thegap'is again at the predetermined value when the' decrease in voltage inthe circuit of solenoid 33" will cause bar 3| to-retum to its previousposition. If the resistance of the gap'increases bar 3| will move toremove resist ance out of the generator field circuit to increase thecurrent output until the predetermined resistance of the gap isreestablished when bar 28 V will move back to its previous position. Inthis mannerthe fusion rate of hollow electrode It will be maintainedconstant for the full period of operation.

Since the granular materials are fedinto hollow electrode ii at aconstant rate, the constituents supplied by hollow electrode l5 and thegranular materials will constantly be fused at the gap in thepredetermined proportions and the final metal will be of uniformanalysis through? out. Furthermore, this result will be obtained withoutthe necessity of maintaining a sufficiently termined resistance value ofsaid gap to supply 1 tween its end and the conductive body, an electriclarge pool of molten metal to average varying rates of supply of theconstituents.

In A. C. operations it will sometimes be preferable to substitute forgenerator 24 and its asso-' elated devices and arrangements, atransformer of low reactance. The transformer should preferably be soarranged that its reactance can be adjusted to the best values forselected discharge voltages.

when a low reactance trans- 7d connecting theoutput to contact device IIand to mold I: should be kept to a minimum. Such" i a transformer,properly adjusted, and with an output circuit of low reactance, willautomatically vary the current output inversely as the resistance of thedischarge gap varies as required, to fuse electrode l5 at a constantrate.

I claim:

1. In metal fusing apparatus, means for feeu' ing a metal electrode at asubstantially constant rate toward a conductive body for fusion by thedischarge of electric current through a gap be tween its end" and theconductive body, electric current supply means connected to saidelectrode and said body for discharge of .electric current through saidgap, and means for altering the electric current supply as required tomaintain the fusion rate of said metal electrode substantially constant.

2. In metal fusing apparatus, means for feeding a metal electrode at asubstantially constant rate toward a conductive body for fusion by thedischarge of electric current through a gap bei tween its end and theconductive body, electric current supply means-connected to said metalelectrode and said body for discharge of electric 7 current through saidgap, said electric current supply means being adapted at a predeterminedresistance value of said gap to supply electric current at th raterequired to fuse said metal electrode at a rate equal to its rate 'ofsupply and means eifective to vary the rate of supply of electriccurrent inversely as the resistance value of said gap varies to maintainthe fusion rate of said metal electrode substantially constant.

3. In metal fusing apparatus, means for feeding a metal electrode at asubstantially constant rate toward a conductive body for fusion by thedischarge of electric current through a gap between its end and theconductive body, electric current generator means having one side of itsoutput connected to said metal electrode and the other side connected tosaid conductive body for discharge of electric current through said gap,said generator means being adapted at a predeeleetric-current at therate required to fuse said metal electrode at the rate supplied, andmeans effected by electric energy variations hi the output circuit ofsaid generator means for varying the electric current output of saidgenerator means as required to substantially constantly fuse said metalelectrode at the rate supplied.

4. In metal fusing'apparatus, meansfor feed-. ing a metal electrode at asubstantially constant rate toward a conductive body for fusion by thedischarge of electric current through a gap becurrent generatorincluding an excitable field having one side of its outputconnected tosaid metal electrode and the other side connected to said conductivebody fordischarge of electricfcurrent through said gap, said generatorbeing adapted at a predetermined resistancevalue of said gap to supplyelectric current at the rate required to fuse said metal electrode at apredetermined rate, and means actuated in accordance with electricenergy variations in the output circuit of said generator for varyingthe excitation of said field inversely as the resistance of said gapvaries'to vary the electrical output of said generator as required tosubstantially constantly fuse said metal electrode at the predeterminedrate.

5. In metalfusing apparatus, means for feed- I former is employed thereactance of the cables ing a metal electrode at a substantiallyconstant rate toward a conductive body for fusion by. the discharge ofelectric current through a gap between its end and the conductive body,an electric current generator having one side of its output connected tosaid metal electrode and the other side connected to said conductivebody for discharge of electric current through said gap. said generatorincluding an excitable field and a variable resistance means for varyingthe excitation of said field, said generator being adapted at apredetermined resistance value of said gap to supply electric current atthe rate required to fuse said metal electrode at a predetermined rate,and means actuated in accordance with electric energy variations in theoutput circuit of said generator operatable to vary the ohmicyalue ofsaid variable resistance means as the resistance of said gap varies tothereby vary the output of said generator as required to substantiallyconstantly fuse said metal electrode at the predetermined rate.

6. In apparatus of the character described, means for feeding a metalelectrode made up of constituents of the desired metal at asubstantially constant rate toward a conductive body for fusion by thedischarge of electric current through a gap between the end of the metalelectrode and the conductive bochr, said feeding means being adapted tofeed said electrode at a substantially constant predetermined rate,means for supplying further metal made up of constituents of the desiredmetal to the gap at a constant rate to be fused with the metal of theelectrode, electric current supply means connected to said metalelectrode and said conductive body for discharge of electric currentthrough said gap, said electric current supply means being adapted tosupply electric current at the rate required to fuse said metalelectrode as supplied at a predetermined resistance value of said gap,and means eflective to vary the current supplied by said current supplymeans inversely as the resistance of said gap varies whereby said metalelectrode is fused at a substantially constant rate and a predeterminedproportion between the constituents of the desired metal supplied bysaid metal electrode and said further metal is maintained substantiallyconstant throughout the operation of the apparatus.

7. in metal fusing apparatus, means for feeding a hollow metal electrodemade up of constituents of the desired metal at a substantially constantrate toward a conductive body for fusion by the discharge of electriccurrent through a gap between the end of the metal electrode and theconductive body, said means being adapted to feed said hollow electrodeat a substantially constant predetermined rate, means for supplyingmetal made up of constituents of the desired metal in granular formthrough said hollow electrode to be fused at said gap with the metal ofsaid hollow electrode, said supplying means being adapted to supply saidmetal in granular.

form at a substantially constant predetermined rate, electric currentsupply means connected to said hollow electrode and said conductive bodyfor discharge of electric current through said gap, said electriccurrent supply means being adapted at a predetermined resistance valueof said gap to supply electric current at the rate required to fuse saidhollow metal electrode as supplied and means effective to vary thecurrent supplied by said current supply means inversely as theresistance of said gap 'varies whereby said hollow metal electrode isfused at a substantially constant rate and a predetermined proportionbetween the constituents of the desired metal supplied by said hollowmetal electrode and said granular metal is maintained substantiallyconstant throughout the operation of the apparatus.

8. In the electrical fusion of metals wherein metal is fused by thedischarge of electric current through a gap between the end of metalelectrode and a conductive body, the steps comprising. feeding a metalelectrode at a constant rate to the gap, supplying electric current tothe gap to fuse the electrode at the rate supplied when the resistanceof the gap is at a predetermined value, and varying the current supplyinversely as the resistance of the gap varies to maintain the fusionrate of the metal electrode substantially constant.

9. In the electrical fusion of metals wherein a metal of desiredanalysis is produced by the fusion of its constituents at a gap throughwhich electric current is discharged between the end of a metalelectrode and a conductive body, the steps comprising, feeding a metalelectrode made up of constituents of the desired metal at a constantrate to the gap, supplying metal made up of constituents of the desiredmetal from a source separate from the metal electrode at a constant rateto be fused with the metal of .the electrode, the rate of feed of theelectrode and the rate of supply of the metal from the separate sourcebeing so chosen that the constituents of the desired metal areconstantly supplied in the required proportions, supplying electriccurrent for discharge through the gap at a rate to fuse the metalelectrode as presented when the resistance at the gap is a predeterminedvalue, and adjusting the current imput as the resistance at the gapvaries to substantially constantly fuse the metal electrode aspresented,

10. In the electrical fusion of metals wherein a metal of desiredanalysis is produced by fusion of its constituents at a gap throughwhich electric current is discharged between the end of a metalelectrode and a conductive body, the steps comprising, feeding at asubstantially constant rate to the gap, a hollow metal electrode made upof constituents of the desired metal, discharging electric currentthrough the gap between the end of the metal electrode and theconductive body, the electric current imput to the gap normally beingsuch that the hollow metal electrode is fused at the rate fed when thegap is of a predetermined resistance, varying the electric current imputto the gap inversely as the resistance at the gap varies tosubstantially constantly fuse the electrode at the rate fed, andsupplying at a constant rate through the hollow metal electrode metal ingranular form made up of constituents of the desired metal to be fusedat the gap with the metal of the hollow metal electrode, the rate offeed of the hollow metal electrode and the rate of supply of the metalin granular form be-- ing such that the constituents of the desiredmetal are substantially constantly fused at the gap in the proportionsrequired in the desired metal.

ROBERT K, HOPKINS.

f CERTIFICATE ei corun'tgr 'xolw. Patent Ne. 2,500,670. v .ldvenber' 3,l.4.2'. ROBERT K'. HoPKms.

It is hereby certified that error appears in'the printed specificationof the above numbered patent requiring correction as followa: Page 5,firet column line 56, for the word "speed" re ad --feed line 51,forinctrea'sea" read -deereaeer-j flageLfirst column, line 23 claim 6;fer'apparatus of the character described? read' --metal ifueingapparatta-q and linea 29, 50and 51., same claim, strike out "saidfeeding means foehig adapted to feed said electrode at asu batantiallj'censtant predetermined ratefl} and. lines 57, 58 and 59, cl-aim7,strike out "said means beihgedapted to feed' said hollew electrode at asubstantially censtant predetermined rateahd that the said LettersPatent should be readwith this cerrecti on therein that the same mayconform to the record of the caeeinthe'Pate'nt of Signed and aefled'thia12m day of Jan ur a. n)- 1915.

. Henry Van Arsdale, (Seal) Acting Commissioner of Patents} iCERTIFICATE oi coanacmmf- I Patent No. 2,500,670." Rovenb.er' 3, 194.2".

ROBERT K. HOPKINS.

It 1e hereby certified that erroi' appears inthe printed specificationof the above numbered. patent requiring correction as follows} Page 5,first column, line 56, for theword "speed" read --feed line 51forincirea'ses" read --decreas'es--; age'l first column, line 2 claimfop'apparatus of the character described," read "metal fue1ngapparaci1s--; and l'inea 29 50and 51., same claim, atr ike out saidfeeding means beir'ig 'adapte d to feed said. electrode at asuhetantially 'consfiant predetermined rafiefl'} and lines 57, 5a and59, cl-aim7,st rike out'aid means beihghdapted to feed] said hollowelecti-ode at a substantially compent pn'edeter mined l 'atefi; add thatthe geld Letters Patent should be readwijzh this correction therein thatthe same may conform to the record of case .1n.the'Patent Offies; e I kI a v I I Signed and sealeatniel am day of Janaai'y,-A 15: 191;

. Henry Van Arsdale, (Seal) acting Commissioner of Patents

